Electric vehicles (e.g., power wheelchairs and scooters) have a number of controls by which a user can select options that influence the control of the vehicle.
Some of these are “switch” type controls, to control things that can be in one state or another. Typical examples would be the “POWER ON/OFF” switch, and “HEADLIGHT ON/OFF” switch.
Other controls are “analog” type controls, which control things that can be in a wide range of states, and ideally an infinite number of states. Typical examples would be the “THROTTLE”, by which the user can select any speed between zero and top speed, and the “MAXIMUM SPEED” control, which allows the user to set the top speed to suit a particular environment (e.g., indoors or outdoors).
In the electric vehicle industry “Analog” controls are traditionally implemented using continuously variable resistors (“potentiometers”). These give an infinite amount of resolution but are expensive, impose design difficulties and restrictions, and are prone to physical abuse.
More recently some manufacturers have used “UP” and “DOWN” switches or buttons to approximate analog controls. When used to implement a “MAXIMUM SPEED” control, for instance, these buttons can be used to step up/down to one of a small number (typically 5) preset maximum speed choices. The choice currently selected is normally indicated by a visual indicator (e.g., LED). Often however this small choice of maximum speed options does not allow fine enough control, so that (for instance) it becomes difficult for a user to drive the chair at the same speed as someone walking beside them. The only way around this is to allow more choices of top speed, which means an impractical amount of button pressing to select the required top speed.
The display to indicate which of these many top speeds is currently selected is also problematical, requiring a large and/or expensive display.
An object of the invention is to provide a technique that allows data from push buttons, or other binary input devices, to be used to closely approximate an “analog” control input device, or at least to provide the public with a useful alternative.